A container terminal provided at a land of a harbor for loading or unloading of a container is a base for marine transportation by ships and land transportation by trucks, trains or the like, and berth facilities for ships (container ships), container loading and unloading facilities, container storage facilities and so on are organically constructed therein to facilitate smooth container distribution. Also, the container terminal is organically connected to a land transportation network including loads and railways.
In order to distribute containers without congestion at a harbor, a system for efficiently managing the entire container terminal is required, and also it is important to procure sufficient relevant facilities such as berth facilities for ships (container ships), container landing and carrying facilities, container storage facilities and so on.
In relation to landing/lifting of containers, a gantry crane installed at a container terminal or the like is a crane for a harbor, which has a door or bridge shape, and is used for stacking containers carried by yard tractors or yard trailers (hereinafter, generally referred to as tractors) or loading stacked containers on yard tractors.
FIG. 1 is a diagram schematically showing an appearance of a container terminal. In the container terminal as shown in FIG. 1, if a cargo ship 1000 having a container cargo reaches a harbor, a container is primarily landed by a container crane 2000 installed at the harbor, the landed container is loaded on a yard tractor and carried to a yard storage area, and the moved container is stored by a gantry crane 3000.
On the contrary, s container carried by a yard tractor may also be shipped on the cargo ship 1000 substantially in the same way, in a reversed order.
A yard tractor tows a yard chassis in a container terminal to transport a container between a dock and a container yard. Here, the yard tractor runs a low speed of about 40 km/hr ad uses a high-output engine ensuring high acceleration since it should reach a certain speed within a short time for the purpose of landing works.
As shown in FIG. 1, the yard tractor just moves in container stacking areas A, B, C and D of FIG. 1, due to its special use in the container yard. From the fact that a yard tractor moves only within a predetermined loading area or along a predetermined path, the inventors of the present disclosure have understood that if energy for operating a vehicle can be obtained in each workspace, all problems of a yard tractor of hybrid method which uses a mixture of fossil fuel and electric fuel and a yard tractor of a battery method which operates with a large-capacity battery can be solved together, and from the understanding, the inventors of the present disclosure have proposed Korean Patent Application No. 2010-0117280 (entitled “Tired gantry crane and straddle carrier for receiving power in contactless fashion”) disclosing a yard tractor which receives power from a power supplying unit capable of supplying power in a contactless fashion in a container stacking area or a tractor moving path and its control method.
However, a yard tractor operating at a harbor periodically reciprocates between a quay crane for landing or lifting a container at a ship and a yard crane for stacking a container. However, since lifting and landing points are not fixed, it requires a lot of costs to install a power supplying device over the entire working area. In addition, if a power supplying place is separately designated for charging a battery of a yard tractor, the yard tractor should stop at the designated place for a certain time for charging, which deteriorates work efficiency.